This invention relates to the cutting of predetermined shapes from material such as paper and cloth, and more particularly to an improved method of making a die for cutting such materials and such a die.
Metal dies are used to cut paper and cloth products such as labels, envelopes and other useful objects of predetermined shapes. Conventionally, the making of a die for such a purpose has been time consuming, expensive and labor intensive. For example, the making of an envelope die required some twenty steps. First, a metal template was made from a pattern which represented the planned cutting edge of the die being made. Using the metal template, a forger measured on a bar of rolled steel some 15/32 of an inch thick the length of steel required to make the finished die. When the proper length had been determined an additional two inches was added to serve as a holding point of the steel during forging. The bar was then cut to length. The steel bar was then heated to a red hot stage and the forger then pounded the steel bar into the designated shape using the metal template to obtain the proper shape. When all the features of the pattern had been forged, the "extra" two inch holding piece of steel was sheared off. The two ends of the die at this point were approximately 1/4 of an inch apart. A welder was then used to weld the die together thereby closing up the exterior of the die and leaving an interior opening through the die. After the die cooled, the excess weld was buzzed out with a router and a grinding buzzer. The die then had to be returned to the forger to remove any distortions which occurred due to the welding heat. During this step, the die was pounded back into shape in conformance to the metal template. Thereafter the die was annealed to bring the die into the proper hardness range. A surface grinder was then used to grind the top and bottom surface of the die level. After the surface grinding, the forger would again check the die to make sure that it was still in accordance with the metal template. The cutting edge of the die was then roughed in by machine and then hand filed and grinder buzzers were then used to grind the desired angle of the cutting edge or surface of the die. A stone wheel grinder was then used to remove all excess steel from the outside of the die and the die was then heat treated and placed into the salt draw. Again, the die was checked with the metal template to make sure it was still of the proper shape. All corners and angles of the metal die were then trued up and a surface grinder was used to grind the die to the proper height. A disc side grinder was then used to grind any additional excess metal from the outside and to blend in the appropriate "roll" from the side to the beveled cutting edge. The die was then sand blasted for a smoother finish and hand filed to a sharp cutting edge. As the final two steps, the die was polished and sprayed with a preservative. This process took roughly three man days of labor and required highly skilled artisans. The process for making label dies was similar. Such processes, particularly the heat bending and milling steps, are believed to have introduced a great deal of strain into the finished die. It has also conventionally been the case that label dies have an inclined outer surface, with the angle of inclination being about eight degrees (8.degree.) with the respect to the longitudinal axis of the die. It is believed that increasing this outside angle could improve the cutting characteristics of the die, but such greater angles are not believed to have been achievable using a process such as the one described above.